This topic has come up before and I'm sure you will get a lot of answers, but
here's mine:
Most conventional concrete mixes will typically achieve about 50% of ultimate
strength within 7 days, and will develop about 75% of ultimate strength after
14 days. To answer your question, I have tilted up many crank-ups 2 and 3
weeks after the pour without any incident. I would be reluctant to try in
only one week.
Since the foundation functions as ballast, the main stresses occur in the
vicinity of the anchor bolts, so if you are using a raising fixture, you can
actually achieve some pretty good loads on the anchor bolts while in the
process of tilting it up. If you are using a crane or "cherry picker" to pull
it up into place, there really is not much load imparted on the anchor bolts.
Hope this info is helpful to you. Good luck on your project.
Matt
KM5VI
-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces@contesting.com] On Behalf Of Chris
Wynn via TowerTalk
Sent: Friday, July 24, 2015 10:25 PM
To: towertalk@contesting.com
Subject: [TowerTalk] Concrete Pad for U.S. Tower TX-472
I am in the process of putting up a TX-472. So far, I have been relatively
lucky and things have gone pretty smoothly. I dug the hole using an excavator
and "slightly" over dug it by a few feet. From my initial calculations, I
should have needed just under 8 cubic yards, but ended up pouring 16 cubic
yards (32 tons and $2k more)! So far the concrete has sat for 7 days curing in
the Georgia sun. I have been pretty cautious to keep water on it, and covered
pretty well. I know that the specs call for that concrete to cure for 28 days.
However, how early can I raise this tower? Does anyone have any experience
with cheating the 28 day curing period? I was kind of hoping to raise it at
the 21 day point. I guess the last real job is to trench from the tower back to
the shack. Therefore, I plan on spending the next couple of weeks burying
hardline.....
Thanks y'all and see you in the pile ups!
73's es CUL,
ChrisN4XFA
Christopher L. Wynn
Attorney-at-Law
Christopher L. Wynn, ESQ., P.C.
6716 Church Street, Suite B
Douglasville, Ga., 30134
(770)942-8661 (Landline)
(770)577-1626
chris@chriswynnlaw.com
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